A federal court on Thursday blocked a Texas law that would have required voters to show photo identification, ruling that the legislation would impose “strict, unforgiving burdens” on poor minority voters.

Describing the law as the most stringent in the country, the unanimous decision by a three-judge panel marks the first time that a federal court has blocked a voter-ID law. It will reverberate politically through the November elections. Republicans and Democrats have been arguing over whether tough voter-ID laws in a number of states discriminate against African Americans and Hispanics.

The panel at the U.S. District Court in Washington ruled that Texas had failed to show that the statute would not harm the voting rights of minorities in the state. In addition, the judges found that evidence indicated that the cost of obtaining a photo ID to vote would fall most heavily on African American and Hispanic voters.

Evidence submitted by Texas to prove that its law did not discriminate was “unpersuasive, invalid, or both,” David S. Tatel, a judge on the U.S. Court of Appeals for the District of Columbia Circuit, wrote in the panel’s 56-page opinion. Voting Rights Act cases must be decided by a special panel of three federal judges.

The ruling followed a decision Tuesday by another three-judge panel in Washington that found the Republican-controlled Texas legislature had intentionally discriminated against Hispanics in drawing new legislative districts.

Texas Attorney General Greg Abbott (R) said the state will appeal Thursday’s ruling to the U.S. Supreme Court, which is the next stop in a voting rights case.

“Today’s decision is wrong on the law and improperly prevents Texas from implementing the same type of ballot integrity safeguards that are employed by Georgia and Indiana — and were upheld by the Supreme Court,” Abbott said in a statement.

Legal experts said it is unknown whether the Supreme Court will take the case. Rick Hasen, an election-law specialist at the law school of the University of California at Irvine, said Texas will probably request an emergency injunction from the court that would allow the state to enforce the law during this election cycle.

“If this happens, this will be a major question for the Roberts court, and it would have to be decided in short order,” said Hasen, referring to Chief Justice John G. Roberts Jr.

Texas is the largest state covered by Section 5 of the Voting Rights Act, which requires federal approval, or “preclearance,” of any voting changes in states that have a history of discrimination. Because of Texas’s history of discrimination, the voter-ID law signed last year by its Republican governor, Rick Perry, had to be cleared by the Justice Department.

The department blocked the law in March, saying it would endanger minority voting rights. Last month, Attorney General Eric H. Holder Jr. called the voter-ID law a “poll tax,” referring to fees that some Southern states used to disenfranchise blacks during the Jim Crow era.

The federal court agreed with the Justice Department. The court’s opinion said that among residents who lack other forms of acceptable identification, the burden of obtaining a state voter-ID certificate would weigh disproportionately on minorities living in poverty, with many having to travel as much as 200 to 250 miles round trip.

Under the Texas law, the minimum cost to obtain a voter ID for a resident without a copy of a birth certificate would be $22. The “election identification certificate” is free, but the legislature rejected a proposal to allow people to obtain the necessary supporting documents at no cost.

None of the travel and financial burdens associated with the new law “had ever before been imposed on Texas voters,” Tatel wrote in the opinion.

“A law that forces poorer citizens to choose between their wages and their franchise unquestionably denies or abridges their right to vote,” the opinion said. “Simply put, many Hispanics and African Americans who voted in the last election will, because of the burdens imposed by [thevoter-ID law], likely be unable to vote in the next election.”

Tatel, who was appointed to the appellate court by President Bill Clinton, was joined in the decision by U.S. district judges Rosemary Collyer and Robert L. Wilkins, appointed by presidents George W. Bush and Barack Obama, respectively.

On Tuesday, a separate panel threw out Texas’s redistricting plans, saying the maps drawn by the legislature undermined the political rights of minorities who are responsible for the state’s population growth.

The Obama administration opposed both the Texas voter-ID law and the redistricting plans, contending that they threaten to disenfranchise millions of Latino and African American voters across the state.

“The court’s decision today and the decision earlier this week on the Texas redistricting plans not only reaffirm — but help protect — the vital role the Voting Rights Act plays in our society to ensure that every American has the right to vote and to have that vote counted,” Holder said in a statement Thursday.

The challenges are part of an escalating national legal battle over voter-ID laws that has become more intense because it is an election year. Eight states passed voter-ID laws last year, and critics say those statutes could hurt turnout among minority voters and others, many of whom helped elect President Obama in 2008.

Supporters of the measures — seven of which were signed by Republican governors and one by an independent — say that requiring voters to show specific photo IDs would prevent voter fraud.

Pennsylvania, a crucial battleground state in this year’s presidential election, is on the front line of a bitter split between many Democrats and Republicans over voting rights. A Pennsylvania judge recently allowed a Republican-backed law requiring voters to show IDs to go into effect for this year’s elections, a setback for Democrats and civil rights groups.

In a courtroom just down the hallway from where judges heard arguments over the Texas voter-ID statute, attorneys for the Justice Department and South Carolina are squaring off this week over a similar measure passed by that state’s legislature last year.

The Justice Department rejected the South Carolina voter-ID law in December, and South Carolina sued the government.

Rather than clarifying the situation with other states, the Texas ruling adds to the legal uncertainty. The federal panel emphasized that it was issuing a narrow opinion that pertained only to the Texas law and not to other jurisdictions trying to implement similar laws.

“The State of Texas enacted a voter-ID law that — at least to our knowledge — is the most stringent in the country,” Tatel wrote.

Attorneys for Texas had cited a case in which the Supreme Court upheld Indiana’s voter-ID law. But the federal panel Thursday rejected the comparison. Because of its history of discrimination, Texas, unlike Indiana, has the burden of proving that its law would not disenfranchise minorities, the panel said.

Del Quentin Wilber contributed to this report.

Sari Horwitz covers the Justice Department and criminal justice issues nationwide for The Washington Post, where she has been a reporter for 30 years. Follow her @SariHorwitz.

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